FCC is preparing new rules that could save 10,000 lives a year.

Newly available data shows that 90 percent of 911 calls made from wireless phones in Washington, DC, "were delivered without the accurate location information needed to find callers who are lost, confused, unconscious, or otherwise unable to share their location," an industry-funded group called Find Me 911 reported today.

Just 39,805 calls out of 385,341 over a six-month period ending July 2013 contained latitude and longitude information, the group said. The data, "filed with the FCC by the DC Office of Unified Communications last fall," was obtained from the Federal Communications Commission with a Freedom of Information Act request.

Find Me 911 said carriers can generally provide what's known as "Phase I" data, which the FCC says consists of "the telephone number of the originator of a wireless 911 call and the location of the cell site or base station transmitting the call." Phase II data includes latitude and longitude of the caller and should be accurate "to within 50 to 300 meters, depending on the type of technology used."

The Phase I data showing the nearest cell tower is "too broad to be useful for emergency responders," Find Me 911 said. Only 10.3 percent of wireless 911 calls included the Phase II information.

Verizon and Sprint were the best at providing Phase II data, doing so on 24.6 percent and 23.3 percent of calls, respectively. Leap was able to provide that data on 16 percent of calls. T-Mobile did so on only 3.2 percent of calls, and AT&T was in last at 2.6 percent.

The bad results are largely because "[t]he location technology currently used by most wireless carriers (called A-GPS) depends on a direct line-of-sight to satellites, so it often fails in indoor locations or dense urban areas like the District," Find Me 911 said.

The carriers may not be breaking any rules by not transmitting Phase II data from indoors.

Consumer advocacy group Public Knowledge called the results "shocking and dangerous," and the group noted that 41 percent of US households depend solely on wireless voice service. Improving 911 location data for wireless phones will be a big concern in the planned shift away from traditional landlines.

“When nine in 10 emergency callers in our nation’s capital cannot be located on wireless phones, we know that the requirements for location accuracy must be updated immediately," Jamie Barnett, former chief of the FCC’s Public Safety and Homeland Security Bureau and director of the Find Me 911 Coalition, said in the group's announcement. "Thankfully, the FCC has proposed a strong new rule to help find wireless callers in need, both indoors and outdoors, and this should eliminate any doubt about the importance of rapid adoption of that rule.”

The FCC believes its updated rules, which are not yet final, could save 10,000 lives a year. It would require more accurate location data for calls from indoors within two years.

Editor's note: The original version of this story, which called Find Me 911 a "public interest group," did not include the fact that the group is funded by the company True Position.